In the post a new book by Professor Jeremy Black, an historian who wears the label "conservative" as a badge of honour (as, indeed, he should). This one is a slight departure for him but one that many historians make from time to time. One of them was Andrew Roberts, the dedicatee of the book.

Black's book is entitled "What If? - Counterfactualism and the problem of history". Tory Historian has no doubt that this is a suitably learned discourse and is looking forward to reading it. (The book is published by the Social Affairs Unit.)

The subject of counterfactualism is dear to Tory Historian's heart. Not the sort of fantasy and wishful thinking that some people indulge in but a real counterfactual history is very useful. It is, after all, the only way that historians can conduct anything resembling a control experiment.

One removes one factor from a historic event, a factor that might or might not have been there, and examines all the others anew. Would the same result have ensued if certain possibilities had been different? Quite often the answer is yes. There would have been no significant changes in historical development.

Every now and then, on the other hand, it is possible to see probable differences, thus defining more accurately the importance of particular historic strands.